A humidity generator for temperatures up to 200 ◦C and pressures up to 1.6 MPa

D Vega-Maza, W W Miller, D C Ripple, G E Scace

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

A new humidity generator that produces gas streams of known moisture content at temperatures from 85 °C to 200 °C, absolute pressures from 0.2 MPa to 1.6 MPa, and relative humidities from 10 % to 90 % has been developed. The generator produces a moist gas stream by injecting fixed-rate streams of dry gas and liquid water into a vaporizer, where the water evaporates into the gas. The gas stream passes into a re-entrant radio-frequency (RF) cavity, which serves as our reference hygrometer, and then a test chamber. The present standard uncertainty of the RF hygrometer is 0.6 %, limited by the uncertainty of literature values for the polarizability of water. Dry nitrogen gas purging the pressure transducer line also combines with the moist gas stream downstream of the test chamber and flows through one of a set of capillaries. Modulation of gas flow through the fixed flow impedance of the capillary gives a simple method for controlling pressure. Individual insulated, temperature-controlled aluminum ovens enclose each major component. A larger oven encloses these ovens and their connecting tubing. To minimize corrosion, critical components are constructed of high-nickel alloys. The small total volume (<1 L) and small flow rate (<0.5 L·min−1) reduce operational hazards from steam scalding or from gas explosion.
Original languageEnglish
Pages (from-to)1477-1487
Number of pages11
JournalInternational Journal of Thermophysics
Volume33
Issue number8
Early online date12 Oct 2010
DOIs
Publication statusPublished - Sep 2012

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gas streams
humidity
ovens
generators
hygrometers
test chambers
operational hazards
radio frequencies
gas explosions
vaporizers
gases
water
purging
temperature
nickel alloys
pressure sensors
steam
moisture content
gas flow
corrosion

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A humidity generator for temperatures up to 200 ◦C and pressures up to 1.6 MPa. / Vega-Maza, D; Miller, W W; Ripple, D C; Scace, G E.

In: International Journal of Thermophysics, Vol. 33, No. 8, 09.2012, p. 1477-1487.

Research output: Contribution to journalArticle

Vega-Maza, D ; Miller, W W ; Ripple, D C ; Scace, G E. / A humidity generator for temperatures up to 200 ◦C and pressures up to 1.6 MPa. In: International Journal of Thermophysics. 2012 ; Vol. 33, No. 8. pp. 1477-1487.
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